Drilling apparatus



April 22, 1969 w. D. ELENBURG DRILLING APPARATUS Sheet Filed March 121968 N m & F m A m w MARCUS L. BATES April 22, 1969 w, ELENBURG3,439,757

DRILLING APPARATUS Filed March 12, 1968 Sheet 3 of 2 INVENTOR. WAYLANDD. ELENBURG BY MARCUS L. BATES United States Patent US. Cl. 175-9325 9Claims ABSTRACT OF THE DISCLDSURE A well drilling apparatus forpreventing excessive flow of fluid into a formation while at the sametime maintaining the cones of a bit free from the cuttings. Thisapparatus is comprised of concentrically arranged drilling pipes flowconnected to a sub with the sub having a formation cutting bit attachedto the lower depending end thereof. The sub and bit includelongitudinally extending passageways, with one such passageway centrallyextending through the sub and bit and into communication with the tubinglocated within the drill pipes, and with the remaining passageways beingradially arranged to communicate with the annulus of the drill pipes. Acylindrical downwardly depending skirt is rigidly attached to the suband downwardly depends about the drill bit, thereby enclosing the drillshanks therewithin. A weir in the form of a plate member is attachedbetween adjacent shanks and is spaced apart from and enclosed by thelower terminal end of the skirt thereby providing a passageway for cleandrilling fluid which flows from the drill pipe annulus and between theweir and skirt. The passageway forces the clean fluid to flow in closeproximity of the drill cones to thereby maintain the cones free ofdebris in an improved manner. This action also removes large formationcuttings from the vicinity of the drill bit so as to prohibit furtherreduction in their size, thereby effecting a savings in the expenditureof power which must be used by the cone, as Well as immediatelyreturning large cuttings or chips of the formation to the surface foranalysis.

Background of the invention Drilling wells by utilizing concentricallyarranged drill pipe wherein the outer drill pipe is threaded at eachdepending end to permit connections to be effected therebetween in theusual manner, and wherein a concentrically located tubing is positionedwithin the outer drill pipe in a manner whereby the depending endssealingly cooperate together to permit rapid connections between theentire assembly to be effected has grown in popularity in the drillingart. The purpose of the concentrically arranged drill pipe is to permitrapid return of large cuttings to the surface of the earth while at thesame time maintaining the cones of a tri-cone bit, for example, free ofdebris; that is, reground cuttings. This combination of elements isespecially useful in carrying out a continuous sampling operationwherein the chips produced by the action of the bit are used forobtaining geological information. This operation continuously recoverslarge pieces of formation to thereby permit continual analysis of theformation since every particle of the drilled formation must passthrough the tubing which is located within the drill pipe. Therefore,the likelihood of hold-up of the drilled chips is minimized and at thesame time loss of fluid up the annulus formed by the drill pipe and thebore hole is minimized.

The drilling fluid may be either liquid or air. Where the bore holepasses through an aquifer, air is often utilized in the form of an airlift by pumping air down through the annulus while air and water arerapidly returned to the surface through the centrally located tubmg.

3,439,757 Patented Apr. 22, 1969 Summary of the invention The presentinvention comprehends an improved sub and an improved bit for use in awell drilling apparatus which prevents excessive flow of fluid into aformation while at the same time maintains the cones of a bit free fromthe cuttings. This apparatus is comprised of concentrically arrangeddrilling pipes flow connected to a sub with the sub having a formationcutting bit attached to the lower depending end thereof. The sub and bitinclude longitudinally extending passageways with one of the passagewayscentrally extending through the sub and bit and into communication withthe tubing located within the drill pipes, and with the otherpassageways radially extending in a manner to communicate with theannulus of the drill pipes. A cylindrical downwardly depending skirt isrigidly attached to the sub and downwardly depends about the drill bit,thereby enclosing the drill shanks therewithin. A weir in the form of aplate member is attached between adjacent shanks and is spaced apartfrom and enclosed by the lower terminal end of the skirt therebyproviding a passageway for the clean drilling fluid which flows from thedrill pipe annulus and between the Weir and skirt. The passageway forcesthe clean fluid to flow in close proximity of the drill cones to therebymaintain the cones free of debris in an improved manner. This actionfurther prevents the bit from balling up in sticky formations, as wellas removing large formation cuttings from the vicinity of the drill bitso as to prohibit further reduction in their size. This effects asavings in the expenditure of power which must be used by the cone, aswell as immediately returning large cuttings or chips of the formationto the surface for analysis.

Therefore, a primary object of the present invention is the provision ofa combination drill bit and sub which includes an improved circulationpattern to thereby enable an improved chip drilling operation to becarried out.

Another object of the present invention is the provision of a sub incombination with a bit and includes a simple modification which iseffected upon a conventional bit to thereby enable an improved sub anddrill bit combination.

Still another object of the present invention is the provision of animproved sub and bit combination which includes radially arrangedpassageways which are always in communication with one another when thebit and sub are made-up.

A further object of the present invention is the provision of animproved flow passageway associated with a drill bit and sub formaintaining the cutting teeth of the bit free of debris.

Another object of the present invention is the provision of a drill bitand sub combination which maintains the drill bit free of debris,permits the rapid return of large chips which are loosened from theformation by the cone of the bit, and which reduces the powerexpenditure required in order to rotate the bit.

The above objects are attained in accordance with the present inventionby the provision of a drill bit and sub combination which are fabricatedin a manner whereby passageways are always aligned with each other whenthe bit and sub are made-up, with one passageway being arranged wherebyfluid flow is directed across the forma* tion cutting cone in animproved manner.

These and other objects of the present invention will become evident asthe remainder of the present disclosure is digested.

Brief description of the drawings FIGURE 1 is a longitudinalcross-sectional view of a drill bit and sub made in accordance with thepresent invention;

FIGURE 2 is a fragmentary elevational view of the lower depending end ofthe present invention;

FIGURE 3 is a fragmentary representation illustrating a portion of thecombination seen in FIGURE 1, taken substantially along lines 3-3 ofFIGURE 1;

FIGURE 4 is a side elevational view of part of the device seen in FIGURE1, with some parts being broken away for clarity;

FIGURE 5 is similar to FIGURE 4 and sets forth a modification thereof;and

FIGURE 6 is a cross-sectional view taken along lines 6-6 of FIGURE 1.

Description of the preferred embodiments Looking now to the details ofthe drawings, and particularly to FIGURE 1, there is seen illustrated atool joint, hereinafter called a sub, which attaches to a drill collaror outer pipe of a dual string by means of threads 12 in a manner knownto those skilled in the art. A second set of threads 14 are provided atthe lower portion of the sub in order to threadedly receive a tri-conerock bit, hereinafter called a bit. A downwardly depending skirt,generally indicated by the arrow at numeral 16, is rigidly attached tothe sub with the outer periphery of the skirt being coextensive withthat of the sub. Abrasive welding at 18 secures the skirt to the subwhile at the same time provides a hard surfacing material for wearpurposes and for maintaining the gauge of the bore hole. The lowerdepending marginal edge portion of the skirt is also provided with hardsurfacing material as indicated by the numeral 20, with the lowermostedge portion of the skirt being indicated by the numeral 22. A centrallylocated passageway 26 longitudinally extends through both the bit andsub with the inside peripheral wall 28 being formed by a return tubeinner-pipe connector 32 which telescopingly receives the inside surfaceof the tubing of the before mentioned drill pipe. The connector isrigidly affixed to shoulder seat 30 by any suitable means, oralternatively can be made an integral port of the sub.

Radially spaced apart from the connector are a series of passageways,two of which are seen at 34 and 36, and each of which flow connect to afirst annular chamber 38, with the last named chamber being formedbetween the before mentioned skirt and sub.

Four spaced apart passageways 40 each communicate the first annularchamber with a second annular chamber 44 with the second annular chamberbeing formed between the skirt and the main body of the bit.

The inside peripheral wall of the lower depending marginal edge portionof the skirt, indicated by numeral 50, is sealingly received by ashoulder, generally indicated by the arrow at numeral 52, whichcircumferentially extends about the outer periphery of the downwardlydepending shank of the bit, thereby leaving an edge portion at 54against which the skirt and bit mate together in abutting relationship,and leaving the bit shank exposed as indicated by the arrow at numeral56. Each cone 58 includes teeth 60 thereon with the cone being rotatablyattached to the shank in the usual manner. While three cones areillustrated herein, other numbers of cones may be em ployed while stillremaining within the scope of the present invention.

A weir or baflle plate, generally indicated by the arrow at numeral 62,is attached along upper edge portion 64 to adjacent shanks with the weirbeing spaced apart from the inside peripheral wall surface of the skirtto thereby form a passageway 66 therebetween.

Each weir is secured to adjacent depending shanks in a manner wherebythree passageways are formed with each passageway being defined by theskirt, weir, and adjacent shanks, assuming the modified bit to be of atri-cone design.

As seen in FIGURE 2 in conjunction with FIGURE 5, the weir is upwardlysloped at 62' so as to provide ample clearance between the upwardlyrotating teeth of the cone and the lowermost edge portion of the weir,while at the same time fluid is forced across the cone teeth in animproved manner. Where deemed desirable, however, the lowermost edgeportion can be maintained horizontal with respect to the bit as seen at62 in FIGURE 5. Sometime it is also advantageous to modify the skirt byproviding the lower marginal edge portion thereof with a cut-out asindicated by the arrow at numeral 70.

Operation In operation, the sub and bit are connected together and to adual drill pipe. The dual drill pipe consists of an outer main drillpipe which rotatably turns the bit and which threadedly cooperates withthe threads of the sub as indicated by numeral 12. The drill pipe isscrewed to gether with other joints of drill pipe in the usual manner.As the various pipe threads are made-up, the inner pipe, or inner tubing(not shown) telescope together with a suitable ring seal such as anO-ring so as to leave concentrically arranged drill pipes having aninside flow passageway and an annular flow passageway. This arrange mentpermits drilling fluid to flow down through the annular or outerpassageway, through radially spaced apart passageways 34 and 36, andinto the first annular chamber. The flow then continues through one ofthe four passageways 40 to where it enters the second annular chamberwhich in turn is flow connected to one of the three passageways formedbetween each of the, depending shanks. As the fluid flows down betweenthe passageway formed between the weir and lower depending end of theskirt as seen at 66 in FIGURE 1, the fluid is forced across the weir,where it is forced to flow in intimate contact across the bit teeth asit continues toward the central passageway. Therefore the fluid flow isforced to follow the path described between the shanks which support thecones, to thereby enhance cleaning of the cone as well as immediatelyplacing large chips into suspension before they are re-ground intosmaller pieces. Fragments of the formation mix together with the fluidand continue to flow upwardly through the central passageway 26 of thebit and inner return tube connector whereupon the flow then continues upthrough the centrally located tubing of the drill pipe.

Accordingly, the weir together with the skirt directs the flow of water,air, or a combination thereof, as well as other drilling fluid about thecones of the bit in an improved manner. This action efiiciently andrapidly removes large chips of formation which results in a moreefiicient drilling operation as well as providing a more desirable meansof rapidly obtaining core samples for geological study. In stickyformations, the bit is less likely to become balled up" for the reasonthat debris of this nature will become intermingled with the intimateflow of fluid thereabout due to the improved circulation in the conearea which is brought about by the skirt and the weir. This also reducesthe tendency of fluid to return up the hole annulus.

It will be noted that the four passageways 40 are arranged with respectto the three passageways formed between the shanks in a manner wherebyflow is always effected between the sub and bit, regardless of theresulting relative position of the former with respect to the latterwhen the bit and sub are made-up or threadedly mated at 14. Furthermore,should the bit design fail to leave a second annular chamber, such asseen at 44, it is considered within the comprehension of this inventionto further modify the bit to thereby provide flow communication betweenpassageway 66 and passageways 40.

As noted when comparing FIGURE 1 with FIGURES 4 and 5, the relativeposition of the lowermost edge portions of the skirt and weir may bearranged wherebythe skirt depends below the weir (FIGURE 5) or where theskirt is located substantially above the weir (FIG- URE 4). Where thedrilling operation requires no splitstream'ing, the lowermost edgeportion of the skirt is preferably positioned with respect to the weiras illustrated in FIGURE 1 or 5. Depending upon the bit design, this maysometime result in a shoulder design at 52 which does not leave an edgeportion at 54 for abutment between the lower edge of the skirt. Thisrequires closer tolerance between the inside diameter of the skirt andthe shoulder in order to effect a positive seal therebetween. It isconsidered within the comprehension of the present invention toreinforce each shank should the shoulder require the removal of excessmaterial from each bit shank.

The hard surfacing 20 helps to stabilize the bit, reduces circulation ofwater up the hole annulus, and reduces wear on the sub and bit shanks.

The present invention enables a standard rock bit, such as theillustrated tri-cone bit of FIGURE 1, to be utilized as a part of thepresent novel combination by merely machining a shoulder as seen at 54of FIGURE 1, for example, in order to sealingly accommodate the downwarddepending terminal end of the skirt. The three weirs (assuming atri-cone bit) are easily installed as an integral part of the bit bymerely welding the weir between adjacent shanks of the bit in spacedapart relationship with respect to the skirt. A tri-cone =bit requiresonly three weirs.

When drilling in hard rock formation, it is advantageous to slope thelower terminal end portion of the weir as seen in FIGURES 2 and 4 inorder to prevent the upwardly traveling teeth of the cone from carryinga hard chip around with it whereupon it may strike the weir causingdamage to the apparatus. When the weir is sloped in a manner asillustrated in FIGURES 2 or 4, and since the drill stem conventionallyturns in a direction to cause the teeth of the cone of FIGURE 2 to bemoving upwardly with respect to the lower portion of the weir, the areabetween the lower edge of the weir and the teeth of the cone isincreased by sloping the weir in the above described manner. Whendrilling through formations which do not pose this problem, the bottomedge portion of the weir can be maintained horizontally disposed asillustrated in FIGURE 5.

As further seen in FIGURE 5, it is sometime desirable to provide themarginal edge portion of the lower depending end of the skirt with asemicircular cut-out, as generally illustrated by the arrow at numeral70. The cutout facilitates flow of fluid back up the annulus of the holewhere it lubricates the outer peripheral surface of the drill pipe,sometime referred to as split streaming, where a part of the fluid isdeliberately returned up the outside of the drill pipe with the majorfluid flow occurring up the inside tubing of the drill string.

Accordingly, it will now be appreciated by those skilled in the art thatthe novel sub of the present invention can be utilized in conjunctionwith a multiplicity of different drill bits by merely eflecting theillustrated modifications upon a standard bit. The modification includesthe provision of a shoulder which can be formed on the bit in aconventional turning lathe. The weirs may be in the form of theillustrated plate members which are best welded between each adjacentshank which supports the cone of the bit. The sub and bit are preferablyfabricated as two separate units, as illustrated in the figures of thedraw- The foregoing is considered as illustrative only of the principlesof the invention. Further, since numerous modifications and changes willreadily occur to those skilled in the art, it is not desired to limitthe invention to the exact construction and operation shown anddescribed, and accordingly all suitable modifications and equivalentsmay be resorted to, falling within the scope of the invention asclaimed.

I claim:

1. A well drilling apparatus for preventing excessive flow of fluid intoa formation by restricting the major flow of drilling fluid to dualpassageways of concentrically arranged drilling pipe, comprising, incombination:

a sub and a formation cutting bit, said sub having fastener means forremovably securing said bit to the drilling pipe;

means forming a centrally located passageway longitudinally extendingthrough said sub and said bit, means forming radially spaced apartpassageways through said sub;

said bit including a main body member, spaced apart cones, and spacedapart shanks with each said cone being connected to said main body byone of said shanks;

means forming a circumferentially extending shoulder about the outerperiphery of said main body;

means forming a coextensive downwardly depending.

cylindrical skirt member having an upper end attached to said sub and alower end slidably received about said shoulder,

a weir attached to adjacent shanks and spaced apart from said skirt tothereby form a flow passageway between said shank and said skirt;whereby:

fluid flow from said radially spaced apart passageways flows between theweir and skirt, into close proximity of the cones, and through thecentrally located passageway to thereby remove the formation as it iscut away by the cones.

2. The combination of claim 1 wherein said weir is rigidly attachedbetween adjacent shanks to thereby cause fluid to flow between the weirand skirt, about the lowermost edge portion of the weir, and across thebit cones.

3. The combination of claim 1 wherein said weir is downwardly sloped inthe direction of the rotation of the bit to thereby prevent damage tothe trailing edge portion of the weir.

4. The combination of claim 1 wherein the lowermost edge portion of saidskirt extends in a downward direction to a lower position as compared tosaid weir.

5. The combination of claim 1 wherein said weir is attached to adjacentshanks in a manner to thereby cause fluid to flow between the weir andskirt, about the lowermost edge portion of the weir, and across the bitcones; and

said weir is downwardly sloped in the direction of the rotation of thebit to thereby prevent damage to the trailing edge portion of the weir.

6. The combination of claim 1 wherein said weir is downwardly sloped inthe direction of the rotation of the bit to thereby prevent damage tothe trailing edge portion of the weir;

said lowermost edge portion of said skirt extends in a downwarddirection to a lower position as compared to the weir.

7. The improvement of claim 1 wherein said bit includes three cones, andfour said radially spaced apart passageways are provided to therebyassure communication between each passageway formed by the weir, andeach said radially spaced apart passageway.

8. he improvement of claim 1 wherein said bit is a conventional tri-conebit which is modified by fabricating said shoulder thereon, and bywelding said weirs in the recited positions.

9. The improvement of claim 1 wherein the lowermost edge portion of saidweir is parallel to the lowermost edge portion of said skirt.

References Cited UNITED STATES PATENTS 2,894,727 7/1959 Henderson -321 X3,151,690 10/1964 Grable 175325 X 3,208,539 9/1965 Henderson 175215DAVID H. BROWN, Primary Examiner.

US. Cl. X.R.

